Amines are one of the most common classes of organic molecules. They play important roles in a variety of areas, ranging from the pharmaceutical industry to plastics manufacturing.
Current methods for the synthesis of amines generally rely on multi-step processes that convert a variety of amine precursors to the amino (NH2) functional group itself. To date, with the singular exception of two existing methodologies, there has been no general method for the direct synthesis of amines from ammonia. Since ammonia is an inexpensive bulk commodity chemical that is manufactured on a multi-ton scale annually, any process that allows for the direct use of ammonia for the introduction of the amino group is therefore highly desirable.
Research into the addition of allyl organometallics to carbonyl compounds and their derivatives continues to proceed unabated—a consequence of the fact that the resulting homoallylic products have proven to be valuable synthons [Denmark, S. E. and Almstead, N. G., Modern Carbonyl Chemistry, ed. Otera, J. Wiley-VCH, Weinheim, 2000, ch. 10; Yamamoto, Y. and Asao, N., Chem. Rev., 1993, 93, 2207; and Roush, W. R., Comprehensive Organic Synthesis, ed. Trost, B. M., Fleming, I. and Heathcock, C. H., Pergamon, Oxford, 2nd edn., 1991, vol. 2, pp 1-53]. The majority of the research, however, has focused on the addition of allylboronic esters to aldehydes. For example, the reaction of
has previously been described by Kobayashi et al. [M. Sugiura, K. Hirano and S. Kobayashi, J. Am. Chem. Soc., 2004, 126, 7182-7183; S. Kobayashi, K. Hirano and M. Sugiura, J. Chem. Commun., 2005, 104-105].
A methodology for the diastereoselective addition of allyl- and crotyl-boronic acids to ketones in the presence of methanolic ammonia to produce tertiary homoallylic amines was recently reported [Dhudshia, B., Tiburcio, J. and Thadani, A. N. Chem. Commun. 2005, 5551-5553].